The invention relates to improved compositions based on lubricants and comprising succinic acid semi-amides and to the use of those lubricant compositions in improving the use properties of lubricants, such as hydraulic or metal-working fluids, greases, gear oils or engine oils.

A composition comprising a) At least one compound of formula Wherein R, is a substituent selected from the group consisting of C1C22alkyl, C2C22alkyl substituted by hydroxy, C2C22alkyl interrupted byC (=O), OC (=O) or by NRaC (=O), C3C22alkyl interrupted by O, S, NRa, C (=O)O or by C (=O)NRa, wherein Ra denotes hydrogen or C,C22alkyl, phenyl, benzyl, 1or 2phenylethyl, 2phenoxyethyl, furfuryl, 1naphthyl, 1naphthylmethyl, cyclo hexyl, cyclohexylmethyl and isobornyl ; R2 and R3 are hydrogen, or one of R2 and R3 is hydrogen and the other is methyl ; and X is carboxy or carboxylate and Y+ is a saltforming cation suitable for lubricant compositions; or X is derivatised carboxy selected from the group consisting of cyano, carboxy esterified by C1C22alkyl, carboxy esterified by hydroxyC2C22alkyl, carboxy es terified by C2C22alkyl interrupted byC (=O),C (=O)O or byC (=O)NRa, carboxy esterified by C3C22alkyl interrupted by O, S, NRa, OC (=O) or by NRa(C=O), wherein Ra denotes hydrogen or C1C22alkyl, carboxy esterified by phenyl, benzyl, 1or 2phenylethyl, 2phenoxyethyl, furfuryl, 1naphthyl, 1naphthylmethyl, cyuclohexyl, cyclohexylmethyl, isobornyl, and carbamoyl of the partial formula Wherein Rb and Rc are each independently of the other hydrogen, C1C22alkyl or 2hydroxyethyl, or Rb and Rc together are C2C8alkylene, C2Csalkenylene, C2C8alkadienylene or C2C8alkylene, C2C8alkenylene or C2C8alkadienylene interrupted by O or byNRa, with Ra being as defined; and Y+ is a hydrogen ion or is a saltforming cation suitable for lubricant compositions; and b) A base oil of lubricating viscosity.

2.

A composition according to claim 1, comprising a) At least one compound (I), wherein Ri is a substituent selected from the group consisting of C1C22alkyl, C2C22alkyl substituted by hydroxy, C2C22alkyl interrupted byC (=O), OC (=O) or by NRaC (=O), C3C22alkyl interrupted by0,S,NRa,C (=O)Oor by C (=O)NRa, wherein Ra denotes hydrogen or C1C22alkyl, phenyl, benzyl, 1or 2phenylethyl, 2phenoxyethyl, furfuryl, 1naphthyl, 1naphthylmethyl, cyclo hexyl, cyclohexylmethyl, and isobornyl ; R2 and R3 are hydrogen, or one of R2 and R3 is hydrogen and the other is methyl ; X is derivatised carboxy selected from the group consisting of cyano, carboxy esterified by C1C22alkyi, carboxy esterified by hydroxyC2C22alkyl, carboxy es terified by C2C22alkyl interrupted byC (=O),C (=O)O or byC (=O)NRa, car boxy esterified by C3C22alkyl interrupted by0,S,NRa,0C (=O) or by NRa(C=O), wherein Ra denotes hydrogen or C1C22alkyl, carboxy esterified by phenyl, benzyl, 1or 2phenylethyl, 2phenoxyethyl, furfuryl, 1naphthyl, 1naphthylmethyl, cyclohexyl, cyclohexylmethyl, isobornyl, and carbamoyl of the partial formula (A), wherein Rb and Rc are each independently of the other hy drogen, C1C22alkyl, or 2hydroxyethyl, or Rb and Rc together are C2C8alkylene, C2C8alkenylene, C2C8alkadienylene or C2C8alkylene, C2C8alkenylene or C2C8alkadienylene interrupted by O or byNRa, with Ra being as defined; and Y+ is a hydrogen ion or is a saltforming cation suitable for lubricant compositions; and b) A base oil of lubricating viscosity.

3.

A composition according to claim 1, comprising a) At least one compound (I), wherein R, is a substituent selected from the group consisting of C1C22alkyl, C2C22alkyl interrupted byC =O) or by OC(=O), C3C22alkyl interrupted byO,Sor by C (=O)O, phenyl and benzyl ; R2 and R3 are hydrogen; X is derivatised carboxy selected from the group consisting of cyano, carboxy esterified by C1C22alkyl, carboxy esterified by hydroxyC2C22alkyl, carboxy es terified by C2C22alkyl interrupted byC (=O) or byC (=O)O, carboxy esterified by C3C22alkyl interrupted by O, S or byOC (=O), and carbamoyl of the partial formula (A) defined as heterocyclylcarbonyl ; and Y+ is a hydrogen ion, ammonium, (C1C4alkyl)14aminoum or (2hydroxy ethyl) 4ammonium ; and b) A base oil of lubricating viscosity.

4.

A composition according to claim 1, comprising a) At least one compound (I), wherein R, is a substituent selected from the group consisting of C1C22alkyl, C3C22alkyl interrupted by O, phenyl, and benzyl ; R2 and R3 are hydrogen; X is derivatised carboxy selected from the group consisting of cyano, carboxy esterified by C1C22alkyl, carboxy esterified by C3C22alkyl interrupted by O, and carbamoyl of the partial formula (A) defined as piperidinocarbonyi, piperaz inylcarbonyl or morpholinocarbonyl ; and Y+ is a hydrogen ion, ammonium, (C1C4alkyl)14ammonium or (2hydroxyethyl) 4 ammonium; and b) A base oil of lubricating viscosity.

5.

A composition according to claim 1, comprising a) At least one compound (I), wherein R, is a substituent selected from the group consisting of C1C18alkyl, C3C18alkyl interrupted by O, phenyl and benzyl ; R2 and R3 are hydrogen; X is carboxy and Y is ammonium, (C1C4alkyl)14ammonium or (2hydroxyethyl)14 ammonium; or X is carboxylate or derivatised carboxy selected from the group consisting of cyano, carboxy esterified by CiCisaikyi, carboxy esterified by C3Cisalkyl inter rupted byO, and morpholinocarbamoyl ; and Y is hydrogen, ammonium, (C1C4alkyl)14ammonium or (2hydroxyethyl) 14 ammonium; and b) A base oil of lubricating viscosity.

6.

A composition according to claim 1, comprising b) A base oil of lubricating viscosity which is used for hydraulic or metalworking fluids, greases, gear oils or engine oils.

7.

A concentrate comprising at least one compound (I) wherein Ri, R2, R3, X and Y are as defined in claim 1.

8.

A method of improving the use properties of lubricants, which comprises adding to the lubricants at least one composition according to claim 1.

Description:

Succinic acid semi-amides as anti-corrosive agents The present invention relates to compositions comprising succinic acid semi-amides and to the use of those compositions in improving the use properties of lubricants, such as hydraulic or metal-working fluids, greases, gear oils or engine oils.

Additives that have to fulfil demanding tasks, such as a high load-bearing capacity, protection against wear and corrosion, and antioxidant action, are added to lubricants. In addition, the properties of lubricants should not be modified disadvantageously in the presence of con- taminants. Often, in mineral oil industry enterprises, oils are admixed with commercially avai- lable additive concentrates or"packages". Contamination with water, calcium detergents and residues of other lubricants may occur during the mixing process. As a result, the action of the additive components with respect to corrosion is reduced, for example owing to formation of hydrolysis products and precipitation of poorly soluble calcium residues, the latter being especially disadvantageous because they block filter systems.

The present invention relates to the problem of producing lubricant compositions that provide improved protection against corrosion, combined with good compatibility with calcium ions.

It has now been found, surprisingly, that succinic acid semi-amides, which are obtainable by reacting succinic acid anhydride with p-amino acid derivatives, improve the corrosion protec- tion in lubricant compositions whilst at the same time the formation of precipitation products and residues is reduced.

The invention relates to compositions comprising a) At least one compound of formula Wherein Ri is a substituent selected from the group consisting of C1-C22alkyl, C2-C22alkyl sub- stituted by hydroxy, C2-C22alkyl interrupted by-C (=O)-, -O-C (=O)- or by -NRa-C (=O)-, C3-C22alkyl interrupted by-0-,-S-,-NRa-,-C (=O)-O- or by -C (=O)-NRa-, wherein Ra denotes hydrogen or C1-C22alkyl, phenyl, benzyl, 1-or 2-phenylethyl, 2-phenoxyethyl, furfuryl, 1-naphthyl, 1-naphthylmethyl, cyclohexyl, cyclohexylmethyl, and isobornyl ; R2 and R3 are hydrogen, or one of R2 and R3 is hydrogen and the other is methyl ; and X is carboxy or carboxylate and Y+ is a salt-forming cation suitable for lubricant com- positions; or X is derivatised carboxy selected from the group consisting of cyano, carboxy esteri- fied by C,-C22alkyl, carboxy esterified by hydroxy-C2-C22alkyl, carboxy esterified by C2-C22alkyl interrupted by-C (=O)-,-C (=O)-O- or by-C (=O)-NRa-, carboxy esterified by C3-C22alkyl interrupted by-O-,-S-,-NRa-,-O-C (=O)-or by-NRa-(C=O)-, wherein Ra denotes hydrogen or C,-C22alkyl, carboxy esterified by phenyl, benzyl, 1-or 2-phenylethyl, 2-phenoxyethyl, furfuryl, 1-naphthyl, 1-naphthylmethyl, cyclohexyl, cyclohexylmethyl, isobornyl, and carbamoyl of the partial formula Wherein Rb and R, are each independently of the other hydrogen, C1-C22alkyl or 2-hydroxyethyl, or Rb and Rc together are C2-C8alkylene, C2-C8alkenylene, C2-C8alkadienylene or C2-C8alkylene, C2-C8alkenylene or C2-C8alkadienylene inter- rupted by -O- or by-NRa-with Ra being as defined; and Y+ is a hydrogen ion or is a salt-forming cation suitable for lubricant compositions; and b) A base oil of lubricating viscosity.

The compounds (I) have excellent corrosion-inhibiting action combined with good compatibil- ity with calcium ions, which may be present in lubricants especially as constituents of deter- gents.

A preferred embodiment relates to compositions comprising a) At least one compound (I), wherein R, is a substituent selected from the group consisting of C,-C22alkyl, C2-C22alkyl substi- tuted by hydroxy, C2-C22alkyl interrupted by-C (=O)-, -O-C (=O)- or by -NRa-C(=O)-, C3-C22alkyl interrupted by-0-,-S-,-NRa-,-C (=O)-O- or by-C (=O)-NRa, wherein Ra de- notes hydrogen or C1-C2alkyl, phenyl, benzyl, 1-or 2-phenylethyl, 2-phenoxyethyl, furfuryl, 1-naphthyl, 1-naphthylmethyl, cyclohexyl, cyclohexylmethyl and isobornyl ; R2 and R3 are hydrogen, or one of R2 and R3 is hydrogen and the other is methyl ; X is derivatised carboxy selected from the group consisting of cyano, carboxy esterified by C-C22alkyl, carboxy esterified by hydroxy-C2-C22alkyl, carboxy esterified by C2-C22alkyl interrupted by-C (=O)-,-C (=O)-O- or by-C (=O)-NRa-, carboxy esterified by C3-C22alkyl interrupted by-0-,-S-,-NRa-,-0-C (=O)- or by-NRa- (C=O)-, wherein Ra de- notes hydrogen or C-C22alkyl, carboxy esterified by phenyl, benzyl, 1-or 2-phenylethyl, 2-phenoxyethyl, furfuryl, 1-naphthyl, 1-naphthylmethyl, cyclohexyl, cyclohexylmethyl, isobornyl, and carbamoyl of the partial formula (A), wherein Rb and Rc are each inde- pendently of the other hydrogen, C1-C22alkyl or 2-hydroxyethyl, or Rb and Rc together are C2-C8alkylene, C2-C8alkenylene, C2-C8alkadienylene or C2-C8alkylene, C2-C8alk- enylene or C2-C8alkadienylene interrupted by -O- or by-NRa-, Ra being as defined; and Y+ is a hydrogen ion or is a salt-forming cation suitable for lubricant compositions; and b) A base oil of lubricating viscosity.

An especially preferred embodiment corresponds to the following compositions comprising a) At least one compound (I), wherein R, is a substituent selected from the group consisting of C-C22alkyl, C2-C22alkyl inter- rupted by-C (=O)-or by-O-C (=O)-, C3-C22alkyl interrupted by -O-, -S- or by-C (=O)-O-, phenyl and benzyl ; R2 and R3 are hydrogen; X is derivatised carboxy selected from the group consisting of cyano, carboxy esterified by C1-C22alkyl, carboxy esterified by hydroxy-C2-C22alkyl, carboxy esterified by C2-C22alkyl interrupted by-C (=O)- or by-C (=O)-O-, carboxy esterified by C3-C22alkyl interrupted by -O-, -S- or by-O-C (=O)-, and carbamoyl of the partial formula (A) defined as heterocyclylcarbonyl ; and Y+ is a hydrogen ion, ammonium, (C1-C4alkyl)1-4ammonium or (2-hydroxyethyl) 1 4- ammonium; and b) A base oil of lubricating viscosity.

A very especially preferred embodiment relates to compositions comprising a) At least one compound (I), wherein Ri is a substituent selected from the group consisting of C1-C22alkyl, C3-C22alkyl inter- rupted by -O-, phenyl, and benzyl ; R2 and R3 are hydrogen; X is derivatised carboxy selected from the group consisting of cyano, carboxy esterified by C1-C22alkyl, carboxy esterified by C3-C22alkyl interrupted by -O-, and carbamoyl of the partial formula (A) defined as piperidinocarbonyl, piperazinylcarbonyl or morpholi- nocarbonyl ; and Y+ is a hydrogen ion, ammonium, (C,-C4alkyl) 14ammonium or (2-hydroxyethyl) 1 4- ammonium; and b) A base oil of lubricating viscosity.

A likewise very especially preferred embodiment relates to compositions comprising a) At least one compound (I), wherein Ri is a substituent selected from the group consisting of C1-C18alkyl, C3-C18alkyl interrupted by -O-, phenyl, and benzyl ; R2 and R3 are hydrogen; X is carboxy and Y is ammonium, (C1-C4alkyl)1-4ammonium or (2-hydroxyethyl) 4- ammonium; or X is carboxylate or derivatised carboxy selected from the group consisting of cyano, car- boxy esterified by C1-C18alkyl, carboxy esterified by 8alkyl interrupted by -O-, and morpholinocarbamoyl ; and Y+ is hydrogen, ammonium, (C1-C4alkyl)1-4ammonium or (2-hydroxyethyl) 4ammonium ; and b) A base oil of lubricating viscosity.

The compounds (I) are prepared in a manner known per se, for example by addition of a primary amine R,-NH2 to an acrylic acid derivative: (X = carboxy, carboxylate or derivatised carboxy) (Addition of amines to a, p-unsaturated carbonyl compounds) to form a 8-amino acid deriva- tive: Which is acylated with a reactive, functional derivative of succinic acid, for example succinic anhydride or succinic acid monochloride.

DE-A-2 054 649 describes the addition of primary amines to acrylic acid esters and the sub- sequent reaction with succinic anhydride. The compounds described therein can be used, inter alia, as textile adjuvants.

In compounds (I), R2 and R3 are hydrogen, or one of R2 and R3 is hydrogen and the other is methyl. Preferably, R2 and R3 are hydrogen.

When X in compounds (I) is carboxy or carboxylate [-C (=O)-O'], Y+ is a salt-forming cation suitable for lubricant compositions, e. g. ammonium, tetramethylammonium, tetraethylammo- nium or 2-hydroxyethyltrimethylammonium. There is present only one carboxy group in sub- stantially undissociated form [-C (=O)-OH] or in salt form [-C (=O)-O], e. g. with ammonium ions, e. g. ammonium, tetramethylammonium, tetraethylammonium or 2-hydroxyethyl- trimethylammonium.

In a preferred embodiment, X is derivatised carboxy or unsubstituted or substituted car- bamoyl as defined hereinbelow. Y+ is then a hydrogen ion or a salt-forming cation suitable for lubricant compositions.

X defined as carboxy esterified by hydroxy-C2-C22alkyl is, for example, a carboxy group that is esterified by hydroxy-C2-C22alkyl defined hereinabove for Ri, e. g. 2-hydroxyethoxy- carbonyl or 2-or 3-hydroxypropoxycarbonyl.

X defined as carbamoyl of the partial formula A is, for example, carbamoyl, dimethyl-or di- ethyl-carbamoyl. In addition, Rb and Rc may be linked to one another by C2-C8alkylene, e. g.

1, 4-n-butylene or 1, 5-n-pentylene, by C2-C8alkenylene, e. g. 2-butenylene, or by C2-C8alka- dienylene, e. g. 1, 3-butadienylene and, together with-N<, form a heterocycle which may, in turn, contain further hetero atoms, e. g. N or O. In that case, the partial formula A corre- sponds to a heterocyclylcarbonyl substituent, e. g. piperidinocarbonyl, piperazinylcarbonyl or morpholinocarbonyl.

In the compounds (I) described hereinabove, the sum of the carbon atoms present in R, and X is preferably greater than ten.

The definition used for Y+,"a salt-forming cation suitable for lubricant compositions", includes those cations of salt-formers that together with the carboxylate group form metal salts suit- able for lubricant compositions, e. g. alkali metal, alkaline earth metal, zinc (Zn2+) or copper (Cu2+) salts, e. g. sodium, potassium, calcium, zinc2+ or Cu2+ ions.

In a preferred embodiment of the invention, the definition used for Y+,"a salt-forming cation suitable for lubricant compositions", is understood to mean those cations of salt-formers that together with the carboxylate group form suitable, non-metallic salts, e. g. ammonium, (C-C22alkyl), 4ammonium or (2-hydroxyethyl) 4ammonium, e. g. tetramethylammonium, tet- raethylammonium or 2-hydroxyethyltrimethylammonium.

The compounds (I) are readily soluble in oils and can be admixed with a base oil of lubricat- ing viscosity, e. g. a lubricant, in a manner known per se.

Component b) Base oil The definition"base oil of lubricating viscosity"includes, for example, lubricants that can be used for hydraulic or metal-working fluids, greases, gear oils or engine oils.

Suitable lubricants are based, for example, on mineral or synthetic oils or mixtures thereof.

Examples of synthetic lubricants include lubricants based on aliphatic or aromatic carboxylic acid esters, polymeric esters, polyalkylene oxides, phosphoric acid esters, poly-oFolefins or silicones, diesters of a divalent acid with a monohydric alcohol, such as, for example, dioctyl sebacate or dinonyl adipate, triesters of trimethylolpropane with a monovalent acid or with a mixture of such acids, such as, for example, trimethylolpropane tripelargonate, trimethylol- propane tricaprylate or mixtures thereof, tetraesters of pentaerythritol with a monovalent acid or with a mixture of such acids, such as, for example, pentaerythritol tetracaprylate, or com- plex esters of monovalent and divalent acids with polyhydric alcohols, for example a complex ester of trimethylolpropane with caprylic and sebacic acid, or a mixture thereof. Apart from mineral oils there are especially suitable, for example, poly-a-olefins, ester-based lubricants, phosphates, glycols, polyglycols and polyalkylene glycols, and also mixtures thereof with water.

An organic or inorganic thickener can also be added to the mentioned lubricants or mixtures thereof (base grease). Metal-working fluids and hydraulic fluids can be prepared on the basis of the same substances as described hereinabove for the lubricants. Such fluids are fre- quently also emulsions of such substances in water or other liquids.

The compositions advantageously contain from 0.005 to 10.0 % by weight, preferably from 0.01 to 5.0 % by weight, especially from 0.01 to 0.9 % by weight, of compounds (I).

The compositions are used, for example, in hydraulic or metal-working fluids, greases, gear oils, or oils for engines of the Otto, diesel, two-stroke, Wankel or orbital type.

The mentioned ingredients are added to the composition using customary mixing methods in a manner known per se. It is also possible, using the compounds (I) or mixtures thereof and, optionally, further additives, to prepare a concentrate or so-called additive package, which is diluted, as required for use, to a concentration for use in the lubricant in question. The com- position of the components in the concentrate is such that the concentrate is liquid at room temperature without further addition of component b) or a solvent.

The present invention relates also to a concentrate comprising a) at least one compound (I) wherein Ri, R2, R3, X and Y are as defined, optionally further additives, and b) a base oil of lubricating viscosity.

The invention relates also to a method of improving the use properties of lubricants, which comprises adding to the lubricants a composition comprising at least one compound (I) wherein R1, R2, R3, X and Y are as defined.

1.2 3.1 g (0.030 mol) of succinic anhydride are added to 11.9 g (0.030 mol) of the resulting intermediate product, and the clear reaction solution is stirred at 100° for 1 h. The cooled crude product is dissolved in 100 mi of hexane, filtered and washed twice with 40 mi of water. The hexane solution is concentrated by evaporation in a rotary evapo- rator and the residue is dried in vacuo. 13.7 g (92 % of theory) of a clear yellow oil, which crystallises on standing are obtained.

3.2 4.1 g (0.040 mol) of succinic anhydride are added to 16 g (0.040 mol) of the resulting intermediate product, the reaction solution is stirred at 100° for 1 h and the cooled crude product is shaken with 200 ml of hexane and 100 ml of brine (NaCI-saturated).

The middle phase of the three phases is washed a further three times using 30 ml of brine each time and is dissolved in 100 ml of toluene, filtered and concentrated by evaporation in a rotary evaporator; the remaining product is dried in vacuo. 15.6 g (77 % of theory) of a clear yellow oil which becomes turbid on cooling are obtained.

After being in contact for that period, the steel bar is subjected to a visual corrosion test.

Each test is carried out in duplicate. The base formulation is based on a mineral oil of speci- fication SN VG46, which has been stabilised using antioxidants and metal deactivators. The active ingredients under test are used in a concentration of 0.1 mmol/kg (corresponding to 0.03-0. 06 % by weight or 300-600 ppm). See Table 2 for results.

0 : no corrosion 1 : light corrosion (< 6 corrosion sites less than 1 mm in diameter) 2 : moderate corrosion (< 5 % of the surface corroded) 3 : heavy corrosion (> 5 % of the surface corroded) Example 6 Testing for filterabilitv in the presence of calcium ions 0.3 g of distilled water and 30 ppm of calcium in the form of a calcium detergent (6.9 % Ca) are added to 300 g of the test formulation. The mixture is homogenised in a four-blade mixer at the maximum speed of rotation for 5 min.. The emulsion is stored for 96 hours at 70°C (+/-2°C) and then for a further 48 hours at room temperature in the dark. If precipitation is observed, the test is stopped. Before filtration, the test mixture is homogenised again by shaking vigorously for one minute. It is then filtered through a 0. 8 u Millipore0 filter (type AAWP 04700) using compressed air at 1 bar (+/-0.05 bar) positive pressure. The times re- quired to filter 50,100, 200 and 300 ml of test mixture are measured. The filtration index FI is calculated, as the mean of two measurements, in accordance with the following formula (see AFNOR NFE 48-691): FI = (t3oomi-t2oomi)/2 (t100m1-t50m1) Fl = 1 means that no resistance is built up at the filter.

FI < 2 is the requirement for passing the test.

In the event of the filter becoming blocked, a note is made after 60 min. of the volume of oil filtered up until then.